Production of butadiene



Match 20,1945. A E, ORCH 2,371,634

Y PRODUCTION 0F BUTADIENEH Filed May 6, 1945 ATTORNEYS Patented Mar. 20, 1945 monUcrIoN or BUTAnmNE Arthur E. Lorch, Tenaiiy, N. J., assignor to Air Reduction Company, Incorporated, New York, N. Y., a corporation ot New York Application Moy s, 194s, serial No. 485,853

1 Claim.

This invention relates to the production of 1,3--` butadiene irom 1,3-butylene glycol and particularly to improvements aifording a. commercially practicable procedure for the Veconomical recoveryv of the desired product.

In an application Ser. No. 477,939, led March 4, 1943, I described a method of' producing butadiene by' heating 1,3-butylene glycol in relatively 'low concentrations in van inert liquid including a dehydration catalyst, and in the'absence of substantial amounts of water in the liquidphase. The procedure requires the maintenance of a body of a Asuitable liquidat a temperature favorable to the reaction, that is, within the range of 220 to 350 C., the preferred range ,being from 260 to 285 C. The catalyst may be dissolved or suspended inthe liquid. K The glycol is introduced at substantially the rate at which conversion to butadiene occurs, so thatl no lsubstantial amount'oi glycol remains at anytime in the liquid. Suitable liquids for use in the method include diphenyl ethane, hexaethyl benzene, benzyl ether, a mixture of diphenyl and diphenyl oxide known as ,Dowthel'mfA a refined petroleum product known as fNujol, Texas Co. #531 wash oil, a topped fuel oil having aV boiling point of 260-270 C., Bunker C' oil and a'higher alcohol known tothe trade as 'fcyclic Cia alcohol.v VThe liquid selected with the dissolved or, suspended catalystl may be heated .to thedesired temperature by means of a jacketthroughwhicha heat- (Cl. 26H81) In the operation of the method as described, the-liquid carrier ior the catalyst becomes, as the result of continued operation,` fouled or contaminated with compounds the exact composition of which ,is unknown. The introduction of these compounds .results in a gradual reduction of the eiectiveness of the catalyst and consequently the liquid carrier must be removed at intervals from the reactor. It may be discarded, but considerable expense is thereby entailed, and it is desirable to purify andY return the liquid carrier for further use. The liquid carrier can be puriing liquid such as Dowuiofnwr is circulated. .It

-is agitated preferably to ensure adequate contact between the glycol `and the catalyst.

As the catalyst, I prefer toemploy Vfamxn niumphosphate. The term "ammoniumphosmixtures of these salts. It is employed also to include. decomposition products of these phosphates which are subject to modilication vwhen subjected tol temperatures such as those emtioned or the resulting products are active catalysts for the reaction. Ammonium phosphate` f pha is lemployed as a general designation of the tri, di and mono ammonium phosphates or is markedly superior to the phosphate catalysis which have beenk mentioned heretofore ,inV 'the literature concerning dehydration of vl3-butylexie glycol. However, other catalysts may be. em-y ployed. the present invention being directed to an improvement in the eilective operation of active catalysts for the dehydration of 1,3-butylene glycol. Y

vvaried over a considerable range. Ordinary concentrated 'sulphuric acid "of commerce, containlng about 98% by weight sulphm'ic acid, has been Y tion of 1,3-butylene glycol.

ed by vacuum distillation `or a combination `of steam distillationV 1with vacuum distillation.

and the cost of operation would probably exceed the `value o1' the liquid treated.

It is the obiect of the present invention to atford a.l simple and eective-method whereby the carrierliquid may be purified at relatively slight expense and returned for re-use in the dehydra Other objects and advantages-of the invention will be apparent as yit is better understood by reference to the following speciiicationand accompanying drawing, which iapparatus adapted Yfor the practice of the invention. It

will be understood that other typesof apparatus A may be employed.

I have discovered-thatthe carrier liquidexriA f -of the liquid, after separ'aonoithe .catalyst therefrom, with sulphuric acidto separate a.'

sludge, containing most of the impurities subsequent treatment of the liquid atan elevated temperature, for example,- about 300 C.,.with an inert gas such as -ca'rbonv dioxide, nitrogen; or steam. As the result of this. treatment, the im.-

purities accumulated in the carrlerliquid are v separated.y The liquid-caribeV returned then to.

the reactor with suitable additions of they catalyst. T-he removal-of thevimpurities irom'the *yield or riniiioi'iione as inithefoperation involving the use of fresh liquid. I 1,

The strengthof the sulphuricacid used maybe o by simple tests.

' phuric acid which will purify the fouled liquid within a reasonable length of time, as higherl concentrations of sulphuric acid cause the formation of larger amounts of those compounds which require removal by heating in the presence of an inert gas.

AThe proportion of sulphuric acid employed will likewise vary, depending upon the condition of the fouled liquid carrier. Usually about 10 parts by volume of 75% by weight sulphuric acid are added to 100'parts by volume of the fouled liquid. More or less sulphuric acid may be used, depending upon the strength thereof. The required proportions to obtain the desired eiect most economically can be determined readily In the operation, the sulphuric acid maybe added directly to the fouled liquid. It is sometim'es advantageous to ilrst emulsify -the acid with a portion of fresh carrierliquid, that is -liquid which has not been previously used in the dehydration lprocedure. However, this operation is optional and not essential to the invention.

The procedure will be better understood by reference to the drawing, in which 5 indicates a reactor having a jacket 6 through which a suitable liquid such as Dowtherm may be circulated -by means of pipes 1 and 8 to maintain the desired temperature of the dehydration reaction. The reactor 5 is partially illled with a body 9 of the liquid carrier carrying the catalyst suspended therein. 1,3-butylene glycol is introduced through a pipe I and delivered beneath the, surface of the body of liquid 9 which is agitated vigorously by means of an agitator II on a shaft I2 driven from any suitable source of power such as a motor I3. Butadiene formed, together with unreacted and partially reacted glycol and possibly some distillate from the liquid carrier, is delivered through a pipe I4 to a condenser I5 through which cooling water is circulated by rpipes I6 and I1. The unreactedrv glycol and any vapors ,of the carrier liquid are condensed and returned through the pipe I4. The butadiene and partially reacted glycol are delivered through a pipe I8 for further treat- The liquid may be decanted through a series of pipes 35, 36, 31 and 38, controlled by valves 39, 49, 4I and 42 and delivered by a pipe 43 to a tank 44 having a jacket 45 through which a heating liquid such as Dowtherm is circulated by pipes 46 and 41. liquid is thus raised to approximately 300 C. An agitator 48 on a shaft 49 is adapted to be driven from a suitable source of power such as a motor 50. While the liquid is agitated, an inert gas such as carbon dioxide, nitrogen or steam is introduced through a pipe 5I controlled :by a valve 52, and the operation is continued until contaminating materials in the liquid have been removed. It may be withdrawn then through a pipe 53 controlled by a valve 54, and after addition of a suitable proportion of the f catalyst it is ready for reuse in the reactor 5.

A suitable storage tank 55 may be' connected to the pipe 53, and the liquid may be withdrawn as required through a pipe ..56 controlled by a valve 51. v l'7 As an example of the invention, Texas Co. #531 wash oil was used with a catalyst composed of ammonium phosphate supported on Filtercel," in the .liquid phase method of dehydration l of 1,3-butylene glycol as described in my appli'- -cation Ser. No. 477,939. 'I'he method produced a yield of 87%.of butadiene. After continued use, the oil became fouled and even when fresh catalyst was used with the oil the yield of buta-W with the catalyst and reutilized in the dehydration reaction. The yield of butadiene was 86.5%, substantially the same perfomance as that obtained with fresh oil.

a manner as to afford a constant supply of puriment in accordance with the method described in A `4 my application Serial No. 477,939.

When the c arrier liquid has become contaminated by continued use, it is delivered, together with the suspended catalyst. to a pipe Iii-controlled by a valve 20 into a settling tank 2|. The catalyst readily separates on standing, and the liquid carrier may be. withdrawn through a pipe 22 controlled by a valve 23. The I' catalyst is removed from the bottom through a pipe 24 controlled by a valve 25 and may be subjected to any suitable treatment for revivication. The liquid is delivered by a pump 26 and The method `as described avoids the loss of the carrier liquid and thereby reduces the cost of maintaining the dehydration reaction. The necessary equipment is simple and inexpensive, and the 'procedure can be carried out in such ed carrier liquid so that the dehydration of 1,3-butylene glycol may be conducted in a substantially continuous manner.

Various changes may -be made in the procedure and in the details of the apparatus used without departing from the invention or sacricing the advantages thereof.

The method of producing Lil-butadiene from 1,3-butylene glycol which comprises subjecting -the 1,3-butylene glycol to the action of a solid dehydration catalyst `suspended in a heated liquid carrier until the liquid carrier is contaminated, separating the solid catalyst from the liquid carrier, agitating the liquid carrier with sulphuric acid to produces. sludge, separating the liquid from the sludge and subjecting the liquid at a temperature of approximately 300 C. to the action of an Iinert gas, adding the catalyst to the resulting liquid and returning it for further use in glycol.

ARTHUR E. LORCH.

The temperature of the the dehydration of 1,3-butylene 

